The boom of a fire truck raises a fireman (and his equipment - total weight 280 lbf) 60 ft into the air to fight a building fire. (a) showing all of your work and using unity conversion ratios, calculate the work done by the boom on the fireman in units of Btu. (b) if the useful power supplied by the boom to lift the fireman is 3.50 hp, estimate how long it takes to lift the fireman.